The Second Amendment should be annulled. The USA has one of the largest professional armies in the world.
Part of the justification for the 2nd amendment is exactly because of that professional army - the capacity for the populace to create a militia to fight back against the government. Absolute nonsense in a practical sense, of course...
The thing is, there are other places with shitloads of guns (even if the US is still an outlier), and this sort of thing just doesn't happen in those places.
The US has 120 guns per 100 people, compared to England and Wales' 5 or Australia's 14. But, Saudi Arabia has in excess of 50, Serbia 40, Montenegro also 40, and these gun death rates aren't even close, whilst El Salvador, Guatemala and Venezuela lead the gun death rates despite ownership rates of 12, 12.1 and 18.5 respectively.
It's also worth noting the US isn't even in the top 10 for gun deaths per capita, but it's #2 for suicides by firearm per capita, and it's the only country in the world with an appreciable rate of deaths in mass shootings.
If the guns weren't there these suicides would likely be lower (there's some evidence that more people survive other suicide attempts more frequently, and fail to complete attempts by other means more often), and the mass attacks would likely be less frequent, less deadly and have fewer victims. However, culturally the US isn't in a position to wholesale ban the sale of guns like the UK and Australia have done.
The culture of gun use, gun ownership and the depiction of firearms in everyday life in the US is the problem - other people have guns and they don't get used like this. It's a culture that has to change, and if that changes then the wholesale control of gun ownership won't be necessary, but if it doesn't change then the wholesale control of guns isn't a possibility anyway.
It seems that Americans are just too invested in their 'rights' and not invested enough in the responsibilities that come along with those rights, and until that changes these deaths are going to continue to happen.
O.